Turbo compressor and refrigerator

ABSTRACT

A turbo compressor includes an impeller; compression stages having scroll chambers which introduce the refrigerant to the impeller or lead the refrigerant compressed by the rotation of the impeller to the outside; and an oil tank in which a heater is disposed and an lubricant oil is stored, and at least a part of the scroll chambers is disposed in the vicinity of the oil tank.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a turbo compressor and a refrigerator. More specifically, the present invention relates to a turbo compressor capable of compressing a fluid by a plurality of impellers and a refrigerator including the turbo compressor.

Priority is claimed on Japanese Patent Application No. 2009-170191, filed Jul. 21, 2009, the content of which is incorporated herein by reference.

2. Description of Related Art

As a refrigerator for cooling or refrigerating a material to be cooled such as water, there is known a turbo refrigerator or the like including a turbo compressor which compresses and discharges the refrigerant by means of a compressing means equipped with an impeller or the like. In the compressor, when the compression ratio increases, the discharging temperature of the compressor rises and the volumetric efficiency declines. Thus, in the turbo compressor included in the turbo refrigerator or the like as described above, the compression of the refrigerant is often performed so as to be divided into a plurality of stages (for example, see PCT Japanese Translation Patent Publication No. 2008-506885).

In such a turbo compressor, a spiral scroll chamber for leading the compressed refrigerant to the outside of the compressor or for introducing the refrigerant into the inside of the compressor to compress the refrigerant is disposed. Furthermore, the lubricant oil is supplied from an oil tank to sliding parts such as a bearing for rotatably supporting an impeller or the like.

In the turbo compressor and the refrigerator of the related art as described above, when the operation is stopped for a long time, the refrigerant is condensed at the lower part in the scroll chamber. For this reason, before the operation of the compressor restarts, there is a need for an operation of discharging the condensed refrigerant liquid from a drain port disposed or the like under the scroll chamber to the outside, which becomes complicated.

SUMMARY OF THE INVENTION

The present invention provides a turbo compressor and a refrigerator which can automatically discharge the refrigerant from the inside of the scroll chamber to rapidly restart the operation, even if the refrigerant is condensed in the scroll chamber for a long-term operation stop.

According to a first aspect of the present invention, a turbo compressor relating to the present invention includes a case having sliding parts, an impeller which is connected to a shaft portion supported by the sliding part and rotates around an axis, a plurality of compression stages having scroll chambers which introduce the fluid into the impeller or leads the fluid compressed by the rotation of the impeller to the outside, and an oil tank in which a heating source is disposed and an lubricant oil to be supplied to the sliding part is stored, wherein at least a part of the scroll chambers is disposed in the vicinity of the oil tank.

In the turbo compressor, at least a part of the scroll chambers is disposed in the vicinity of the oil tank with the heating source disposed thereon. For this reason, it is possible to preferably transmit the heat of the lubricant heated before the operation restart by the heating source oil from the wall surface of the oil tank to the wall surface of the scroll chamber. In addition, the fluid to be compressed, which has been condensed within the scroll chamber, can be heated by the heat.

Thus, the work of discharging the condensed refrigerant liquid from the drain port or the like disposed under the scroll chamber to the outside is unnecessary, whereby the operation can restart without any particular operations.

According to a second aspect of the present invention, in the turbo compressor relating to the present invention, at least a part of the scroll chamber is disposed under the oil surface of the lubricant oil to be stored in the oil tank. According to the turbo compressor, the heat of the heated lubricant oil can be more preferably transmitted to the scroll chamber.

According to a third aspect of the present invention, a refrigerator relating to the present invention includes a condenser that cools and liquefies the compressed refrigerant; an evaporator which cools a material to be cooled by evaporating the liquefied refrigerant to take the vaporization heat from the material to be cooled; and a turbo compressor which compresses the refrigerant evaporated by the evaporator to supply the refrigerant to the condenser, wherein the above-mentioned compressor is used as the turbo compressor.

The refrigerator exhibits the same working effects as the turbo compressor.

According to the present invention, even if the refrigerant is condensed in the scroll chamber during operation stop, the refrigerant can be automatically discharged from the inside of the scroll chamber to rapidly restart the operation.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing a schematic configuration of a turbo refrigerator relating to an embodiment of the present invention.

FIG. 2 is a vertical sectional view of a turbo compressor included in the turbo refrigerator relating to an embodiment of the present invention.

FIG. 3 is a sectional view taken from lines III-III in FIG. 2.

FIG. 4 is a sectional view taken from lines IV-IV in FIG. 2.

DETAILED DESCRIPTION OF THE INVENTION

An embodiment of a turbo compressor and a refrigerator relating to the present invention will be described with reference to FIGS. 1 to 4.

A turbo refrigerator (a refrigerator) 1 relating to the present embodiment is, for example, installed on a building or a factory so as to create the cooling water for air conditioning. As shown in FIG. 1, the turbo refrigerator 1 includes a condenser 2, an economizer 3, an evaporator 5 and a turbo compressor 6.

The condenser 2 is supplied with a compression refrigerant gas X1, which is a refrigerant (a fluid) such as R134a compressed in a gas state, and makes the compression refrigerant gas X1 a refrigerant liquid X2 by cooling and liquefying the compression refrigerant gas X1. As shown in FIG. 1, the condenser 2 is connected to the turbo compressor 6 via a flow path R1 through which the compression refrigerant gas X1 flows. In addition, the condenser 2 is connected to the economizer 3 via a flow path R2 through which the refrigerant liquid X2 flows. An expansion valve 7 for decompressing the refrigerant liquid X2 is installed on the flow path R2.

The economizer 3 temporarily stores the refrigerant liquid X2 which has been decompressed in the expansion valve 7. The economizer 3 is connected to the evaporator 5 via a flow path R3 through which the refrigerant liquid X2 flows. Furthermore, the economizer 3 is connected to the turbo compressor 6 via a flow path R4 through which gaseous components X3 of the refrigerant generated in the economizer 3 flow. An expansion valve 8 for further decompressing the refrigerant liquid X2 is installed in the flow path R3. The flow path R4 is connected to the turbo compressor 6 so as to supply the gaseous components X3 to a second compression stage 23 described below which is included in the turbo compressor 6.

The evaporator 5 cools a material to be cooled, such as water, by evaporating the refrigerant liquid X2 to take the vaporization heat from the material to be cooled. The evaporator 5 is connected to the turbo compressor 6 via a flow path R5 through which a refrigerant gas X4 generated by the evaporation of the refrigerant liquid X2 flows. The flow path R5 is connected to a first compression stage 22 described below which is included in the turbo compressor 6.

The turbo compressor 6 compresses the refrigerant gas X4 to make it the compression refrigerant gas X1. As described above, the turbo compressor 6 is connected to the condenser 2 via the flow path R1 through which the compression refrigerant gas X1 flows. Furthermore, the turbo compressor 6 is connected to the evaporator 5 via the flow path R5 through which the refrigerant gas X4 flows.

As shown in FIGS. 2 to 4, the turbo compressor 6 includes a case 11 with a plurality of sliding parts 10, a plurality of compression stages 12, and an oil tank 13 in which the lubricant oil LO is stored.

The case 11 is divided into a motor housing 15, a compressor housing 16 and a gear housing 17, and those parts are connected to each other in a separable manner. On the motor housing 15, an output shaft 18 which rotates around an axis O, and a motor 20, which is connected to the output shaft 18 to drive the compression stage 12, are disposed. The output shaft 18 is rotatably supported by a first bearing 21 fixed to the motor housing 15. Herein, the sliding parts 10 include not only the first bearing 21 but a second bearing 26, a third bearing 27, a gear unit 28 or the like as described below.

The compression stage 12 includes a first compression stage 22 which sucks and compresses the refrigerant gas X4 (see FIG. 1), and a second compression stage 23 which further compresses the refrigerant gas X4 compressed in the first compression stage 22 to discharge the refrigerant gas X4 as the compression refrigerant gas X1 (see FIG. 1). The first compression stage 22 is disposed on the compressor housing 16. The second compression stage 23 is disposed on the gear housing 17.

The first compression stage 22 has a plurality of first impellers (impellers) 22 a, a first diffuser 22 b, a first scroll chamber (a scroll chamber) 22 c and a suction port 22 d. The plurality of first impellers 22 a is fixed to a rotational shaft (a shaft portion) 25, is driven for rotation around the axis O by means of the motor 20, and imparts the speed energy to the refrigerant gas X4 which is supplied from a thrust direction to discharge the refrigerant gas X4 in a radial direction. The first diffuser 22 b compresses the refrigerant gas X4 by converting the speed energy imparted to the refrigerant gas X4 by the first impeller 22 a into the pressure energy. The first scroll chamber (the scroll chamber) 22 c leads the refrigerant gas X4 compressed by the first diffuser 22 b to the outside of the first compression stage 22. The suction port 22 d sucks the refrigerant gas X4 to supply the same to the first impeller 22 a. The first diffuser 22 b, the first scroll chamber 22 c and a part of the suction port 22 d is formed by a first housing 22 e surrounding the first impeller 22 a.

A plurality of inlet guide vanes 22 g for adjusting the suction capacity of the first compression stage 22 is installed in the suction port 22 d of the first compression stage 22. The respective inlet guide vanes 22 g can rotate so that external areas from the flow direction of the refrigerant gas X4 can be altered by means of a driving mechanism 22 i.

In the first housing 22 e which is the outer peripheral portion of the first impeller 22 a in the first compression stage 22 and the suction port 22 d at the upstream side thereof, a relay space 22 h, which forms a ring shape centered on the axis O, is dividedly formed. A driving mechanism 22 i for driving the inlet guide vane 22 g is housed inside the relay space 22 h.

The relay space 22 h communicates with the rear surface side of the inlet guide vane 22 g in the suction port 22 d via a slight gap 22 j. As a result, it is configured such that the pressure of the relay space 22 h is always equal to that of the suction port 22 d.

The second compression stage 23 includes a second impeller (an impeller) 23 a, a second diffuser 23 b, a second scroll chamber (a scroll chamber) 23 c and an inlet scroll chamber (a scroll chamber) 23 d. The second impeller 23 a imparts the speed energy to the refrigerant gas X4, which is compressed in the first compression stage 22 and is supplied from the thrust direction, to discharge the refrigerant gas X4 in the radial direction. The second diffuser 23 b compresses the refrigerant gas X4 by converting the speed energy imparted to the refrigerant gas X4 by the second impeller 23 a to the pressure energy to discharge the refrigerant gas X4 as the compression refrigerant gas X1. The second scroll chamber 23 c leads the compression refrigerant gas X1 discharged from the second diffuser 23 b to the outside of the second compression stage 23. The inlet scroll chamber 23 d guides the refrigerant gas X4 compressed in the first compression stage 22 to the second impeller 23 a. Herein, the second diffuser 23 b, the second scroll chamber 23 c and a part of the inlet scroll chamber 23 d is formed by a second housing 23 e surrounding the second impeller 23 a.

The second impeller 23 a is fixed to the rotational shaft 25 such that the rear surface thereof is mated with that of the first impeller 22 a, and the rotational movement force from the output shaft 18 of the motor 20 is transmitted to the rotational shaft 25, so that the rotational shaft 25 rotates around the axis O, whereby the second impeller 23 a is driven for rotation. The second diffuser 23 b is disposed around the second impeller 23 a in the shape of a ring.

The second scroll chamber 23 c is connected to the flow path R1 for supplying the condenser 2 with the compression refrigerant gas X1 to supply the flow path R1 with the compression refrigerant gas X1 led from the second compression stage 23.

In addition, the first scroll chamber 22 c of the first compression stage 22 and the inlet scroll chamber 23 d of the second compression stage 23 are connected with each other via an outside piping (not shown) which is provided separately from the first compression stage 22 and the second compression stage 23, whereby the refrigerant gas X4 compressed in the first compression stage 22 is supplied to the second compression stage 23 via the outside piping. The above-mentioned flow path R4 (see FIG. 1) is connected to the outside piping, whereby the gaseous components X3 of the refrigerant generated in the economizer 3 is supplied to the second compression stage 23 via the outside piping.

The rotational shaft 25 is rotatably supported by the second bearing 26 fixed to the gear housing 17 and the third bearing 27 fixed to the compressor housing 16 in a rotatable manner with respect to the case 11.

In the gear housing 17, an accommodation space S1 is formed which accommodates a gear unit 28 for transmitting the driving force of the output shaft 18 to the rotational shaft 25.

The oil tank 13 is formed and disposed so as to extend from the lower part of the accommodation space S1 to the lower part of the compressor housing 16. The first scroll chamber 22 c, the second scroll chamber 23 c and the lower part sides of the inlet scroll chamber 23 d are disposed so as to be lower than the oil surface L of the lubricant oil LO stored in the oil tank 13.

A heater (a heating source) 30 for heating the lubricant oil LO to a prescribed temperature is disposed in the oil tank 13.

The gear unit 28 includes a low speed gear 31 fixed to the output shaft 18 of the motor 20, and a high speed gear 32 which is fixed to the rotational shaft 25 and is engaged with the low speed gear 31. In addition, the rotational movement force of the output shaft 18 of the motor 20 is transmitted to the rotational shaft 25 such that the revolution count of the rotational shaft 25 increases with respect to the revolution count of the output shaft 18.

Next, the operations of the turbo refrigerator 1 and the turbo compressor 6 relating to the present embodiment will be described.

First of all, along with the operation start of the turbo refrigerator 1 and the turbo compressor 6, the lubricant oil LO is supplied from the oil tank 13 to the sliding parts 10 by means of an oil pump (not shown). Then, the motor 20 is driven, so that the rotational movement force of the output shaft 18 of the motor 20 is transmitted to the rotation shaft 25 via gear unit 28. As a result, the first compression stage 22 and the second compression stage 23 are driven for rotation.

When the first compression stage 22 is driven for rotation, the suction port 22 d of the first compression stage 22 enters a negative pressure state, whereby the refrigerant gas X4 from the flow path R5 flows in the first compression stage 22 via the suction port 22 d. At this time, the suction capacity is suitably adjusted by means of the inlet guide vane 22 g.

The refrigerant gas X4, which has flowed in the first compression stage 22, flows in the first impeller 22 a from the thrust direction, is imparted with the speed energy by the first impeller 22 a and is discharged in the radial direction.

The speed energy of the refrigerant gas X4 discharged from the first impeller 22 a is converted to the pressure energy by the first diffuser 22 b, so that the refrigerant gas X4 is compressed. The refrigerant gas X4 discharged from the first diffuser 22 b is led to the outside of the first compression stage 22 via the first scroll chamber 22 c.

In addition, the refrigerant gas X4 led to the outside of the first compression stage 22 is supplied to the second compression stage 23 via the outside piping.

The refrigerant gas X4 supplied to the second compression stage 23 flows in the second impeller chamber 23 a from the thrust direction via the inlet scroll chamber 23 d and is discharged in the radial direction imparted with the speed energy by the second impeller 23 a.

The speed energy of the refrigerant gas X4 discharged from the second impeller 23 a is converted to the pressure energy by the second diffuser 23 b, whereby the refrigerant gas X4 is further compressed and becomes the compression refrigerant gas X1.

The compression refrigerant gas X1 discharged from the second diffuser 23 b is led to the outside of the second compression stage 23 via the second scroll chamber 23 c.

In addition, the compression refrigerant gas X1 led to the outside of the second compression stage 23 is supplied to the condenser 2 via the flow path R1.

In a case where R134a or the like is used as the refrigerant liquid X2, since the condensation temperature is 30° C. to 40° C., when the turbo refrigerator 1 is stopped for a long time, the refrigerants remaining as the gas in the first scroll chamber 22 c, the second scroll chamber 23 c and the inlet scroll chamber 23 d are condensed in the lower part thereof.

When the operation restarts, the lubricant oil LO stored in the oil tank 13 is heated to the condensation temperature or more of the refrigerant by means of the heater 30. As a result, the heat of the heated lubricant oil LO is transferred from the wall surface of the oil tank 13 to the respective wall surfaces of the first scroll chamber 22 c, the second scroll chamber 23 c and the inlet scroll chamber 23 d, so that the refrigerant, which was condensed in the chamber, is heated. Thus, the refrigerant is evaporated and becomes gas again.

According to the turbo refrigerator 1 and the turbo compressor 6, the first scroll chamber 22 c, the second scroll chamber 23 c and the lower part of the inlet scroll chamber 23 d are disposed in the vicinity of the oil tank 13. For that reason, when the turbo compressor 6 starts, by heating the lubricant oil LO stored in the oil tank 13 with the heater 30, the refrigerants, which are condensed in the first scroll chamber 22 c, the second scroll chamber 23 c and the inlet scroll chamber 23 d, are heated and evaporated, whereby the refrigerants can be automatically discharged from the chamber.

At this time, the first scroll chamber 22 c, the second scroll chamber 23 c and the lower part of the inlet scroll chamber 23 d are disposed at the part lower than the oil surface L of the lubricant oil LO which is stored in the oil tank 13. Thus, the heat of the heated lubricant oil LO can be further preferably transmitted.

Furthermore, the technical scope of the present invention is not limited to the above-mentioned embodiment, but various modifications can be added without departing from the gist of the present invention.

For example, in the above-mentioned embodiments, although the configuration including the two compression stages (the first compression stage 22 and the second compression stage 23) has been described, the present invention is not limited thereto, but a configuration including three or more compression stages may be adopted.

In addition, the turbo compressor, in which the motor housing 15, the compressor housing 16, and the gear housing 17 are each dividedly formed as the case 11, has been described. However, the present invention is not limited thereto, but, for example, a configuration, in which the motor is disposed between the first compression stage and the second compression stage, may be adopted.

While preferred embodiments of the invention have been described and illustrated above, it should be understood that these are exemplary of the invention and are not to be considered as limiting. Additions, omissions, substitutions, and other modifications can be made without departing from the spirit or scope of the present invention. Accordingly, the invention is not to be considered as being limited by the foregoing description, and is only limited by the scope of the appended claims. 

1. A turbo compressor comprising: a case having sliding parts; an impeller which is connected to a shaft portion supported by the sliding parts and rotates around an axis; a plurality of compression stages having scroll chambers which introduce a fluid into the impeller or lead the fluid compressed by the rotation of the impeller to the outside, and an oil tank in which a heating source is disposed and lubricant oils, which are supplied to the sliding parts, is stored, wherein at least a part of the scroll chambers is disposed in the vicinity of the oil tank.
 2. The turbo compressor according to claim 1, wherein at least a part of the scroll chambers is disposed under the oil surface of the lubricant oil which is stored within the oil tank.
 3. A refrigerator comprising: a condenser that cools and liquefies a compressed refrigerant; an evaporator which cools a material to be cooled by evaporating the liquefied refrigerant to take the vaporization heat from the material to be cooled; and a turbo compressor which compresses the refrigerant evaporated by the evaporator to supply the refrigerant to the condenser, wherein the turbo compressor according to claim 1 or 2 is used as the turbo compressor. 